Review
Engineering, Mechanical
Bo Wang, Peng Hao, Xiangtao Ma, Kuo Tian
Summary: Thin-walled structures are commonly used in aerospace and aircraft structures, but accurately predicting the lower-bound buckling load is still a challenge due to geometric imperfections. This paper reviews several new numerical and experimental methods for determining knockdown factors (KDF) and proposes an improved KDF curve based on extensive test data. The new KDFs show an overall improvement compared to the traditional criterion.
ACTA MECHANICA SINICA
(2022)
Article
Materials Science, Multidisciplinary
Arefeh Abbasi, Dong Yan, Pedro M. Reis
Summary: This study focuses on the mechanical response of pressurized spherical shells with a single dimple-like defect to a point probe, characterizing the nonlinear force-indentation response at different pressurization levels through experiments, finite element modeling, and classic shell theory. The critical buckling pressure of the shell can be inferred non-destructively by tracking the maxima of the indentation force-displacement curves, with the effectiveness of probing influenced by the indentation angle. The study also quantifies the characteristic length associated with localized deformation using FEM simulations and shallow shell theory, demonstrating the limitations of applying probing as a non-destructive technique to assess the stability of spherical shells.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2021)
Article
Chemistry, Physical
Wenxian Su, Jie Ren
Summary: This study models and analyzes the local buckling problem of submarine pipelines, and investigates the sensitivity of different shapes and sizes of imperfections. The results show that the critical external pressure of the pipeline is sensitive to imperfections, while the buckling propagation pressure is not. This has significant implications for the design and use of submarine pipelines.
Article
Mechanics
Gaojian Lin, Fei Li, Qiuting Zhang, Pengwan Chen, Weifu Sun, Ivan Saikov, Vladimir Shcherbakov, Mikhail Alymov
Summary: This study investigated the dynamic stability of cylindrical fiber composite shells with metal liner subjected to uniform internal pressure pulse, revealing the pulse buckling of the inner metal liner and vibrational buckling of the outer fiber composite shell. Numerical simulations showed the effect of buckling amplitude of the inner metal liner on the dynamic stability of the outer fiber composite shell.
COMPOSITE STRUCTURES
(2022)
Article
Mathematics, Applied
Davit Harutyunyan, Andre Martins Rodrigues
Summary: This study proves that the buckling load of cylindrical shells under vertical compression depends on the curvature of the cross section curve. For convex curves with uniformly positive curvature, the buckling load has a linear relationship with the shell thickness. For curves with positive curvature at finitely many points, the buckling load lies between C(1)h(8/5) and C(2)h(3/2) for small thickness h > 0.
JOURNAL OF NONLINEAR SCIENCE
(2023)
Article
Engineering, Multidisciplinary
H. N. R. Wagner, G. Niewoehner, A. Pototzky, C. Huehne
Summary: This article reviews experimental results of tori-spherical shells under external pressure, presents detailed numerical elastic-plastic buckling analysis and various geometric imperfection approaches, leading to the development of new design factors that significantly improve critical load estimations.
INTERNATIONAL JOURNAL OF PRESSURE VESSELS AND PIPING
(2021)
Article
Chemistry, Physical
Rogerio R. dos Santos, Saullo G. P. Castro
Summary: This study investigates the application of continuous tow shearing (CTS) in lightweight, cylindrical shell designs to reduce imperfection sensitivity. Machine learning methods, namely Support Vector Machine, Kriging, and Random Forest, are compared to optimize the design. The proposed ML-based framework solves the inverse problem and provides lightweight designs with reduced imperfection sensitivity.
Article
Multidisciplinary Sciences
James Croll
Summary: This paper argues that there has been insufficient consideration of classical shell buckling theory and its reduced stiffness extension in the analysis of shell buckling and the infamous case of the axially loaded cylinder. It suggests that future design should integrate numerical research programs with classically extended buckling theory to effectively exploit the potential benefits of advanced composite materials and rib reinforcement. The results from a longstanding research program show that this integration has resolved important issues and can enhance our ability to design materially efficient shells against buckling.
PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2023)
Article
Engineering, Civil
Xudong Zhi, Guoqing Song, Zheng Li, Feng Fan, Xiaofei Jin
Summary: Stiffening rings are essential for strengthening steel cooling towers. However, there is a lack of research on the sensitivity of steel cooling towers to imperfections, particularly regarding different layouts of stiffening rings. In this study, finite element models were used to analyze the buckling behavior of 160-m-high hyperboloid single-layer reticulated-shell steel cooling towers. Results showed that the imperfection sensitivity of the towers was low and decreased with more stiffening rings. A combined imperfection pattern, based on the lowest buckling mode shapes, was proposed and found to be suitable for different layouts of stiffening rings. The magnitude of imperfection also affected the buckling resistance, with an imperfection magnitude of Hout/300 being recommended.
Article
Engineering, Mechanical
Emmanouil Sakaridis, Nikolaos Karathanasopoulos, Dirk Mohr
Summary: This paper proposes a machine learning based methodology for predicting the buckling response of tubular structures. By generating a large dataset and evaluating the model, it is demonstrated that this method can accurately predict the crushing response of the structures.
INTERNATIONAL JOURNAL OF IMPACT ENGINEERING
(2022)
Article
Multidisciplinary Sciences
Fabien Royer, Sergio Pellegrino
Summary: This paper investigates the stability of space structures composed of open-section thin shells connected by thin rods, under the action of pure bending moment. Probing experiments were conducted to study the localized deformation in the post-buckling regime of these structures, which is highly sensitive to imperfections. The results provide insights into efficient buckling criteria for operating these structures near their buckling limits, reducing their mass significantly.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SCIENCES
(2023)
Article
Engineering, Civil
Xiangtao Ma, Fayao Wang, Huiping Wang, Peng Hao, Bo Wang
Summary: It is found that considering imperfection sensitivity is necessary for optimizing VS composite cylinders, as linear buckling analysis results are not robust. By establishing an optimization framework considering imperfection sensitivity, significant improvements can be made to the critical moment and knockdown factor of composite cylinders.
THIN-WALLED STRUCTURES
(2021)
Article
Mechanics
Yosef Dayan, David Durban, Sefi Givli
Summary: This study provides an in-depth investigation of the postbuckling behavior of an elastic fiber constrained inside a rigid cylinder, focusing on the fiber deformation and contact stages during initial postcontact. It also examines the effect of fiber geometrical imperfection and provides new understanding of the influence of key parameters on the behavior of such systems.
JOURNAL OF APPLIED MECHANICS-TRANSACTIONS OF THE ASME
(2022)
Article
Engineering, Aerospace
Chang-Hoon Sim, Do-Young Kim, Min-Hyeok Jeon, Jae-Sang Park, In-Gul Kim, Joon-Tae Yoo, Young-Ha Yoon, Keejoo Lee
Summary: Nonlinear postbuckling analyses were conducted to investigate the buckling KnockDown Factors (KDF) for pressurized metallic cylinders. Various numerical modeling techniques were used to represent the initial imperfections of the cylinder. The study found that the selection of appropriate initial imperfection modeling methods is necessary considering the internal pressure levels of the cylinder.
INTERNATIONAL JOURNAL OF AERONAUTICAL AND SPACE SCIENCES
(2023)
Article
Mechanics
Yachuan Sun, Zhen Liu, Jie Sun, Fang Ren, Hao Cheng, Longlei Dong
Summary: This paper investigates the snap-through response of a rectangular clamped carbon fiber reinforced silicon carbide composites (C/SiC) plate under high temperature and progressive wave acoustic load, considering boundary elasticity and initial imperfections. The study establishes a dynamic model for the plate and updates boundary stiffnesses and imperfection coefficients based on experimental results. The results show a significant correlation between snap-through occurrence and response spectra evolution, indicating that factors like plate thickness and initial imperfections play a crucial role in snap-through prediction, which is essential for hypersonic aircraft structure design.
COMPOSITE STRUCTURES
(2021)
Article
Engineering, Civil
S. Niemann, H. N. R. Wagner, C. Huehne
Summary: In the collaborative FP7 project PoLaRBEAR, a high-performance anisogrid prepreg structure concept was developed and tested under uniaxial compression. The anisogrid structures consist of stiffeners with different directions and a load bearing skin, with special interface layers for proper connection. Experimental results showed manufacturing-induced geometric imperfections causing slight curvature in the panel.
THIN-WALLED STRUCTURES
(2021)
Article
Engineering, Manufacturing
Sander van den Broek, Johannes Wolff, Sven Scheffler, Christian Huehne, Raimund Rolfes
Summary: This study presents an approach to improve the fatigue life of additively manufactured structures and simultaneously reduce the influence of random variations in local thickness.
PROGRESS IN ADDITIVE MANUFACTURING
(2022)
Article
Mechanics
Johannes Wiedemann, Robert Prussak, Erik Kappel, Christian Huehne
Summary: FBG sensors are commonly used for characterizing residual stress in composite materials, but have limitations in absolute strain measurements, while strain gages can achieve absolute strain measurements. Despite being applied to metal layers, sensors can still analyze the cure state of resin, and the effects of different cure cycle modifications on residual stress should be considered.
COMPOSITE STRUCTURES
(2022)
Article
Chemistry, Physical
Nicola Cersullo, Jon Mardaras, Philippe Emile, Katja Nickel, Vitus Holzinger, Christian Huehne
Summary: A detailed characterization of the fatigue and damage tolerance behavior of structural components is required for the widespread application of Additive Manufactured (AM) technology in the aircraft industry. Metal AM techniques are prone to internal defects, which have a detrimental effect on fatigue properties. In this study, Ti6Al4V and Inconel 718 coupons with artificially induced defects were produced using the Laser Powder Bed Fusion (LPBF) technique. Fatigue tests were performed, and it was observed that Inconel was more defect tolerant compared to Titanium. A simplified stress-life-defect size model based on fracture mechanics was devised and validated using experimental test results and fracture surface analysis.
Article
Polymer Science
Chresten von der Heide, Julian Steinmetz, Oliver Volkerink, Patrick Makiela, Christian Huhne, Michael Sinapius, Andreas Dietzel
Summary: An integrable sensor inlay for monitoring crack initiation and growth inside bondlines of structural carbon fiber-reinforced plastic (CFRP) components is presented. The sensor system, which measures strain at two successive fronts inside the bondline, can recognize cracks in the proximity of the inlay regardless of the mechanical loads. The proposed sensor system has good adhesion and high fatigue strength, and is of great importance for structural adhesive bonding in lightweight CFRP constructions.
Article
Materials Science, Composites
Johannes Wiedemann, Jan-Uwe R. Schmidt, Christian Huehne
Summary: Residual stresses in fiber metal laminates (FML) that occur during the manufacturing process can be quantified using asymmetric specimens. The curvature of the laminates can be correlated with the stress-free temperature, which can be used to quantify residual stress levels in more complex FMLs. This research presents a comprehensive investigation of FML specimens to identify influencing parameters and develop a workflow for residual stress characterization using asymmetric specimens.
JOURNAL OF COMPOSITES SCIENCE
(2022)
Article
Mechanics
O. Voelkerink, J. Koord, E. Petersen, C. Huehne
Summary: Failure behavior prediction of carbon fiber reinforced plastics (CFRP) is challenging due to the multiple damage mechanisms involved. This study compared different modeling strategies for Progressive Damage Analysis (PDA) using an Open Hole Tension (OHT) test campaign. Two recommended modeling strategies were identified: an efficient variant based solely on Continuum Damage Mechanics (CDM) and a more complex variant combining CDM with Fracture Mechanics (FM) to simulate interlaminar failure.
MECHANICS OF COMPOSITE MATERIALS
(2023)
Article
Instruments & Instrumentation
Tilmann Barth, Johannes Wiedemann, Thomas Roloff, Tim Behrens, Natalie Rauter, Christian Huehne, Michael Sinapius, Rolf Lammering
Summary: In this work, the dispersive relation of guided ultrasonic waves (GUWs) in fiber metal laminates (FMLs) made of carbon FRP and steel is experimentally determined. Multi-frequency excitation signals and laser scanning vibrometry are used to measure the resulting wave field. The data are processed and analyzed in the frequency-wavenumber domain, showing excellent agreement with numerical solutions.
SMART MATERIALS AND STRUCTURES
(2023)
Article
Engineering, Multidisciplinary
Patrick Meyer, Michael Vorhof, Josef Koord, Cornelia Sennewald, Chokri Cherif, Christian Huehne
Summary: This study investigates the mechanical properties of woven flexure hinges for pressure-actuated cellular structures. The stiffness of anisotropic flexure hinges can be determined through simple mechanical tests, and the mechanical properties of a double-layer hinge configuration are superior to those of a single-layer configuration.
COMPOSITES PART B-ENGINEERING
(2023)
Article
Engineering, Multidisciplinary
J. Koord, O. Voelkerink, E. Petersen, C. Huehne
Summary: This article investigates delamination in fiber metal laminates, particularly in combinations of carbon fiber reinforced plastics and steel. The interface behavior is studied using the double cantilever beam and end-notched flexure tests. It is found that the analysis of asymmetric laminates should consider the effect of thermal residual stresses.
COMPOSITES PART B-ENGINEERING
(2023)
Article
Materials Science, Multidisciplinary
P. Meyer, J. Finder, C. Huehne
Summary: This study presents novel test methods for measuring the bending stiffness of variable cross-section flexure hinges under large deformations and pure bending loading. The test methods are based on tensile test, four-point bending test, and column bending test, and they are validated using isotropic materials.
EXPERIMENTAL MECHANICS
(2023)
Article
Engineering, Aerospace
Patrick Meyer, Christian Huhne, Kjell Bramsiepe, Wolf Krueger
Summary: This study verifies the feasibility of the actuated adaptive wingtip concept through aeroelastic analysis and shows that the pressure-actuated cellular structures (PACS) made from glass-fiber-reinforced plastic can bear the loads acting on the wingtips of a Cessna Citation X. The adaptive-stiffness hinge reduces the wing root bending moment and maintains the wing's stability in flight.
JOURNAL OF AIRCRAFT
(2023)
Article
Engineering, Manufacturing
Ferdinand Cerbe, Dominik Mahlstedt, Michael Sinapius, Christian Huehne, Markus Boel
Summary: 4D printing with FDM allows for the production of smart structures using smart materials that can change their shape over time. This article investigates the relationship between stress and strain during 4D printing by varying printing parameters and analyzing the resulting forces and curvatures. The results show that different printing parameters affect the programming force and post-activation curvature differently.
PROGRESS IN ADDITIVE MANUFACTURING
(2023)
Article
Engineering, Electrical & Electronic
Henning Schlums, Christian Huhne, Michael Sinapius
Summary: This study investigates the application of herringbone bearings for supporting high-speed rotating shafts in order to ensure the operational reliability of fuel cell systems. Optimizing the bearing design can improve stability and lift-off speed in the entire speed range. The findings of this study can serve as a reference for bearing design in other high-speed applications.
Article
Engineering, Electrical & Electronic
Maximilian Neitmann, Tom Rothe, Erik Kappel, Christian Huehne
Summary: This study proposes a method to achieve high-rate assembly processes by combining mobile units with lightweight assembly jigs that have deformation compensation capability. The end effector with shape compensation function can compensate for manufacturing tolerances and gravity effects, effectively counteracting shape deviations.
Article
Engineering, Civil
Jian Xue, Weiwei Zhang, Jing Wu, Chao Wang, Hongwei Ma
Summary: This study integrates a plate-type local resonator with varying free boundaries within a plate to convert the initial low-order global vibration modes into localized vibration modes. A novel semi-analytical method is proposed to analyze the free vibration of the plate with thickness and displacement discontinuities. The results show that by applying free boundary conditions, the low-order localized vibration frequencies can be significantly reduced without affecting the low-order global frequencies.
THIN-WALLED STRUCTURES
(2024)
Article
Engineering, Civil
Merve Tunay
Summary: In recent years, there has been an increasing number of studies on the mechanical properties of sandwich structures manufactured with the Fused Deposition Modeling (FDM) method. However, there is still a lack of experimental data on the mechanical characteristics of FDM-manufactured sandwich structures under different thermal aging durations. In this experiment, the energy absorption capabilities of sandwich structures with different core geometries were investigated under various thermal aging durations. The results showed that the core topology significantly influenced the energy absorption abilities of the sandwich structures.
THIN-WALLED STRUCTURES
(2024)
Article
Engineering, Civil
Zi-qin Jiang, Zi-yao Niu, Ai-Lin Zhang, Xue-chun Liu
Summary: This paper proposes a crosssection corrugated plate steel special-shaped column (CCSC) that improves the bearing capacity and overall stability of structural columns by using smaller material input. Through theoretical analysis and numerical simulation, the overall stability of the CCSC under axial compression is analyzed. The design method and suggestions for the stability of CCSC are put forward. Compared with conventional square steel tube columns, the CCSC has obvious advantages in overall stability and steel consumption.
THIN-WALLED STRUCTURES
(2024)
Article
Engineering, Civil
Yong Zhang, Yangang Chen, Jixiang Li, Jiacheng Wu, Liang Qian, Yuanqiang Tan, Kunyuan Li, Guoyao Zeng
Summary: A hybrid TPMS method was proposed to develop a new TPMS structure, and the mechanical properties of different TPMS structures were studied experimentally and numerically. Results showed that the hybrid TPMS structure had higher energy absorption and lower load-carrying capacity fluctuation. Further investigations revealed that the topological shape and material distribution had significant influence on mechanical properties, and the hybrid additive TPMS structure exhibited significant crashworthiness advantage in in-plane crushing condition.
THIN-WALLED STRUCTURES
(2024)
Article
Engineering, Civil
Tongfei Sun, Ye Liu, Kaoshan Dai, Alfredo Camara, Yujie Lu, Lijie Wang
Summary: This paper presents a series of experimental and numerical studies on the performance of a novel double-stage coupling damper (DSCD). The effects of damper configuration, friction-yield ratio (Rfy), and loading protocol on the hysteresis performance of the DSCD are investigated. The test results demonstrate that the arrangement of ribs in the DSCD increases its energy dissipation capacity. Numerical analysis reveals that the length of the friction mechanism and the clearance between the yield segment and the restraining system affect the energy dissipation and stability of the damper.
THIN-WALLED STRUCTURES
(2024)
Article
Engineering, Civil
Jeonghwa Lee, Young Jong Kang
Summary: This study investigates the local buckling behavior and strength of I-shape structural sections by considering flange-web interactions through three-dimensional finite element analysis. The study provides a more reasonable estimation of local buckling strength by considering the ratio of flange-web slenderness and height-to-width ratio, and presents design equations for flange local and web-bend buckling coefficients.
THIN-WALLED STRUCTURES
(2024)
Article
Engineering, Civil
Yizhe Chen, Wenfeng Xiang, Qingsong Zhang, Hui Wang, Lin Hua
Summary: This study investigates the surface modification of a nickel plate to improve the bonding strength with carbon fiber-reinforced plastics (CFRP). The results show that different surface modification methods, including sandblasting, coupling agent treatment, and compound coupling agent treatment, significantly enhance the bonding strength of CFRP/Ni joints. The research provides insights into improving the connection between nickel and CFRP, as well as other heterogeneous materials.
THIN-WALLED STRUCTURES
(2024)
Article
Engineering, Civil
Agha Intizar Mehdi, Fengping Zhang, Moon-Young Kim
Summary: A spatial stability theory of mono-symmetric thin-walled steel beams pre-stressed by spatially inclined cables is derived and its validity is demonstrated through numerical examples. The effects of initial tension, deviator numbers, inclined cable profiles, and bonded/un-bonded conditions on lateral-torsional buckling of the pre-stressed beams are investigated, with a specific emphasis on the effects of increasing initial tension.
THIN-WALLED STRUCTURES
(2024)
Article
Engineering, Civil
Teng Ma, Jinxiang Wang, Liangtao Liu, Heng Li, Kui Tang, Yangchen Gu, Yifan Zhang
Summary: The structural response of water-back plate under the combined action of shock wave and bubble loads at water depths of 1-300 m was numerically investigated using an arbitrary Lagrange-Euler method. The accuracy of the numerical model was validated by comparing with experimental and theoretical results. The influences of water depth and length-to-diameter ratio of the charge on the combined damage effect were analyzed. The results show that as water depth increases, the plastic deformation energy of the water-back plate decreases, and the permanent deformation mode changes from convex to concave. When the charge has a large length-to-diameter ratio, the plastic deformation energy of the radial plate is higher than that of the axial plate, and the difference decreases with increasing water depth. Increasing the length-to-diameter ratio enhances the combined damage effect in the radial direction in deep-water environments.
THIN-WALLED STRUCTURES
(2024)
Article
Engineering, Civil
Qiu-Yun Li, Ben Young
Summary: This paper investigates the flexural performance of CFS zed section members bent about the neutral axis parallel to the flanges through experimental and numerical analysis. The results show that the current direct strength method generally provides conservative predictions for the flexural strength of unstiffened zed section members, but slightly unconservative design for edge-stiffened zed section beams. The nominal flexural strengths of zed section members with edge stiffeners were found to be underestimated by 17% to 21% on average. Modified DSM formulae are recommended for the design of CFS zed section beams.
THIN-WALLED STRUCTURES
(2024)
Article
Engineering, Civil
Weinan Gao, Bo Song, Xueyan Chen, Guochang Lin, Huifeng Tan
Summary: This paper presents a precise method for predicting deformation in large-scale inflatable structures, utilizing finite element modeling and laser scanning technique. The study shows a good agreement between the predictive model and non-contact measurement results.
THIN-WALLED STRUCTURES
(2024)
Article
Engineering, Civil
Fei Gao, Zongyi Wang, Rui Zhu, Zhenming Chen, Quanxi Ye, Yaqi Duan, Yunlong Jia, Qin Zhang
Summary: This research investigates the mechanical properties of high-strength ring groove rivet assemblies and the load resistances of riveted T-stubs. Experimental tests reveal that Grade 10.9 rivets have higher yield strength and strain, and lower ultimate strain, making them suitable for high-strength ring groove rivet connections. Increasing the rivet diameter benefits the T-stubs, while increasing the flange thickness is not always advantageous. The Eurocode 3 method is not suitable for T-stubs connected through ring groove rivets, while the Demonceau method is conservative.
THIN-WALLED STRUCTURES
(2024)
Article
Engineering, Civil
Shangchun Jiang, Liangfeng Sun, Haifei Zhan, Zhuoqun Zheng, Xijian Peng, Chaofeng Lue
Summary: This study investigates the bending behavior of two-dimensional nanomaterials, diamane and its analogous structure TBGIB, through atomistic simulations. It reveals that diamane experiences structural failure under bending, while TBGIB bends elastically before undergoing structural failure. The study provides valuable insights for the application of these materials in flexible electronics.
THIN-WALLED STRUCTURES
(2024)
Article
Engineering, Civil
Qiang Zhang, Jianian Wen, Qiang Han, Hanqing Zhuge, Yulong Zhou
Summary: In this study, the mechanical properties of Q690 steel H-section columns under bi-directional cyclic loads are investigated, considering the time-varying characteristics of corrosion. A refined finite element (FE) model is built to analyze the degradation of mechanical property and failure mechanisms of steel columns with different design parameters during the whole life-cycle. The study proposes a quantitative calculation method for the ultimate resistance and damage index of steel columns, taking into account the ageing effects. The findings emphasize the importance of considering the ageing effects of steel columns in seismic design.
THIN-WALLED STRUCTURES
(2024)
Article
Engineering, Civil
Yuda Hu, Qi Zhou, Tao Yang
Summary: The magneto-thermo-elastic coupled free vibration of functionally graded materials cylindrical shell is investigated in this study. The vibration equation in multi-physical field is established and solved using the Hamilton principle and the multi-scale method. The numerical results show that the natural frequency is influenced by various factors such as volume fraction index, initial amplitude, temperature, and magnetic induction intensity.
THIN-WALLED STRUCTURES
(2024)